Analysis Package P9 : Lignocellulosic Sugars and Lignin

The Organic Fraction of Municipal Solid Waste (OFMSW) contains paper and cardboard, an attractive cellulosic feedstock for bioethanol production. Waste paper/cardboard (WPC) was subjected to mild acid treatment in solids loadings from 20 to 27.5 %. Different doses of commercial enzyme cocktail and various adjuvants facilitating enzymatic saccharification were tested. Enzyme dosing of 3.75 FPU/g fiber with very slow fed-batch saccharification of 27.5 % (w/v) solids from model lignin-free paper pulp resulted in 12.6 % (w/v) total sugar after 74 h. Use of cheap non-catalytic waste protein adjuvants including Soymeal, Protisyr, Feather meal strongly improved enzymatic saccharification and reduced the overall process cost by reducing commercial enzyme dosing. After fermentation with the industrial yeast strain BMD44 (Cellusec 1.0) an ethanol titer of 5.77 % (v/v) was obtained using a reduced enzyme loading of 2.5 FPU/g of actual industrial WPC fiber. These results show the potential of economically profitable second-generation bioethanol production with WPC fiber.

Biochar is an engineered carbon-rich substance used for soil improvement, environmental management, and other diverse applications. To date, the understanding of how biomass affects biochar microstructure has been limited due to the complexity of analysis involved in tracing the changes in the physical structure of biomass as it undergoes thermochemical conversion. In this study, we used synchrotron x-ray micro-tomography to visualize changes in the internal structure of biochar from diverse feedstock (miscanthus straw pellets, wheat straw pellets, oilseed rape straw pellets, and rice husk) during pyrolysis by collecting a sequence of 3D scans at 50 C intervals during progressive heating from 50 C to 800 C. The results show a strong dependence of biochar porosity on feedstock as well as pyrolysis temperature, with observed porosity in the range of 7.41-60.56%. Our results show that the porosity, total surface area, pore volume, and equivalent diameter of the largest pore increases with increasing pyrolysis temperature up to about 550 C. The most dramatic development of pore structure occurred in the temperature range of 350-450 C. This understanding is pivotal for optimizing biochar's properties for specific applications in soil improvement, environmental management, and beyond. By elucidating the nuanced variations in biochar's physical characteristics across different production temperatures and feedstocks, this research advances the practical application of biochar, offering significant benefits in agricultural, environmental, and engineering contexts.

Polymer materials today face significant challenges, notably the utilization of green and low-carbon feedstock, the development of eco-friendly preparation processes, and effective material recycling. A promising solution to these challenges lies in the direct synthesis of covalent adaptable networks (CANs) from biomass sources, like lignin. However, the development of unmodified lignin CANs via catalyst-free methods has been a challenging task. Here, we report the successful preparation of lignin-based CANs (TERs) via phthalate monoester transesterification. In this system, lignin (PB1000) serves as hard segment and crosslinker, while the soft segment consists of a biomass diol (PripolTM 2033). By blending the ratio of hard to soft segments, we were able to tune the mechanical properties of the TERs (with lignin content ranging from 10 to 50 wt% and crosslink density increasing from 3600 mol/m3 to 47900 mol/m3). Monoester bonds within the TERs are highly dynamic at elevated temperatures (with an activation energy of 169.2 kJ mol-1), facilitating material recycling without the need for catalysts. Furthermore, TERs can be chemically recycled via alkaline solutions at 80 C. Notably, we demonstrate a potential application for this work in the form of a TER-based adhesive. In addition to its excellent adhesion properties, the TER adhesive exhibits thermal repair ability, removability, and degradability properties. This work provides a green and sustainable approach towards tackling the challenges associated with recycling of thermoset plastics.

The organic fraction of municipal solid waste (OFMSW) and refuse-derived fuel (RDF) mainly consisting of paper/cardboard can be used as feedstock for the production of cellulosic ethanol. In this paper, an efficient technology is described to convert waste paper/cardboard into cellulosic ethanol. The process involves separation of the OF from the other components in the waste stream. An acid pretreatment is used to liberate the cellulosic fibers and the accessibility of the enzyme Cellic CTEC3 loading 3.75-11.25 FPU/g paper in a fed-batch addition up to 22.5% solid yield, 15 g sugars/l with a saccharification yield up to 90%. A semi-simultaneous fermentation process (SSFP) with a saccharomyces cerevisae strain MDS130 capable of fermenting both pentoses and hexoses are growing an ethanol titer (%v/v) of 8.4% on pilon-plant scale.

Thallium(I) (Tl(I)) pollution has become a pressing environmental issue due to its harmful effect on human health and aquatic life. Effective technology to remove Tl(I) ions from drinking water can offer immediate societal benefits especially in the developing countries. In this study, a bio-adsorbent system based on nitro-oxidized nanocellulose (NOCNF) extracted from sorghum stalks was shown to be a highly effective Tl(I) removal medium. The nitro-oxidation process (NOP) is an energy-efficient, zero-waste approach that can extract nanocellulose from any lignocellulosic feedstock, where the effluent can be neutralized directly into a fertilizer without the need for post-treatment. The demonstrated NOCNF adsorbent exhibited high Tl(I) removal efficiency (>90% at concentration < 500 ppm) and high maximum removal capacity (Qm = 1898 mg/g using the Langmuir model). The Tl(I) adsorption mechanism by NOCNF was investigated by thorough characterization of NOCNF-Tl floc samples using spectroscopic (FTIR), diffraction (WAXD), microscopic (SEM, TEM, and AFM) and zeta-potential techniques. The results indicate that adsorption occurs mainly due to electrostatic attraction between cationic Tl(I) ions and anionic carboxylate groups on NOCNF, where the adsorbed Tl(I) sites become nuclei for the growth of thallium oxide nanocrystals at high Tl(I) concentrations. The mineralization process enhances the Tl(I) removal efficiency, and the mechanism is consistent with the isotherm data analysis using the Freundlich model.

Synthetic rubber produced from nonrenewable fossil fuel requires high energy costs and is dependent on the presumed unstable petroleum price. Natural rubber latex (NRL) is one of the major alternative sustainable rubber sources since it is derived from the plant 'Hevea brasiliensis'. Our study focuses on integrating sustainably processed carboxycellulose nanofibers from untreated jute biomass into NRL to enhance the mechanical strength of the material for various applications. The carboxycellulose nanofibers (NOCNF) having carboxyl content of 0.94 mmol/g was prepared and integrated into its nonionic form (-COONa) for its higher dispersion in water to increase the interfacial interaction between NRL and NOCNF. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analyses of NOCNF showed the average dimensions of nanofibers were length (L) = 524 +/- 203 nm, diameter (D) 7 +/- 2 nm and thickness 2.9 nm. Furthermore, fourier transform infra-red spectrometry (FTIR) analysis of NOCNF depicted the presence of carboxyl group. However, the dynamic light scattering (DLS) measurement of NRL demonstrated an effective diameter in the range of 643 nm with polydispersity of 0.005. Tensile mechanical strengths were tested to observe the enhancement effects at various concentrations of NOCNF in the NRL. Mechanical properties of NRL/NOCNF films were determined by tensile testing, where the results showed an increasing trend of enhancement. With the increasing NOCNF concentration, the film modulus was found to increase quite substantially, but the elongation-to-break ratio decreased drastically. The presence of NOCNF changed the NRL film from elastic to brittle. However, at the NOCNF overlap concentration (0.2 wt. %), the film modulus seemed to be the highest.

Activated carbons are promising sorbents that have been heavily investigated for the physisorptive storage of hydrogen. The industrial process for production of activated carbons is finely tuned and requires a reliable and uniform feedstock. While the natural biopolymer lignin, a byproduct of several industries, has received increasing interest as a potentially sustainable and inexpensive activated carbon feedstock, the ratio of the three aromatic monomers (S, G, and H) in lignin can be heavily affected by the lignin source and growing conditions. The aromatic ratio is known to influence the thermal behavior of the polymer, which could be problematic for production of consistent activated carbons at scale. With the goal of improving the consistency of activated carbons produced from lignins derived from different feedstocks, here we present a route to limiting the influence of lignin feedstock on activated carbon porosity and performance, resulting in a carbonization process that is resilient to changes in lignin source. Two different types of organosolv lignin (representing high S-unit content and high G-unit content feedstocks) were investigated. Resulting activated carbons exhibited a high surface area (>1000 m2 g-1) with consistent adsorptive properties and reasonable hydrogen uptake of up to 1.8 wt % at 1 bar and -196 C. These findings indicate that low-temperature carbonization conditions can be used to produce a consistent carbon material using organosolv lignins from any source, paving the way for more widespread use of lignin in large-scale carbon production.